Does adolescent heavier alcohol use predict young adult aggression and delinquency? Parallel analyses from four Australasian cohort studies

While the association between heavy alcohol consumption and aggression has been well documented, the causal direction of this association, particularly at a population level, is disputed. A number of causal sequences have been proposed. First, that aggression leads to heavy alcohol use. Second, that heavy alcohol use leads to aggression. Third, that the association between alcohol use and aggression is due to confounding by (a) sociodemographic variables or (b) delinquency. We report here data from four Australasian prospective longitudinal studies of adolescents, to assess the temporal sequence of heavy drinking and aggression over the period from adolescence to young adulthood. The four cohort studies provide a total sample of 6,706 persons (Australian Temperament Project, n = 1701; Christchurch Health and Development Study, n = 931; Mater-University of Queensland Study of Pregnancy, n = 2437; Victorian Adolescent Health Cohort Study, n = 1637). We use multinomial logistic regression to determine whether early adolescent aggression predicts subsequent age of onset of heavy episodic drinking (HED), after adjustment for concurrent sociodemographic factors and delinquency. We then consider whether HED predicts subsequent aggression, after adjusting for past aggression, concurrent delinquency, and a range of confounders. There are broadly consistent findings across the four cohort studies. Early aggression strongly predicts subsequent HED. HED predicts later aggression after adjustment for prior aggression and other confounders. Policies that alter population levels of alcohol consumption are likely to impact on levels of aggression in societies where HED linked to aggression is more common.